Continuous-phase-transformation elastic metasurface for flexural wave using notched structure

Non-Hermitian metagrating for perfect absorption of elastic waves

“…The past decades have witnessed an unprecedented flourishing of metamaterials, 1–7 which exhibit intriguing extraordinary physical properties due to engineered subwavelength microstructures rather than intrinsic material properties of the constituents. In particular, as a family of 2D versions of wave modulation metamaterials, elastic metasurfaces 8–17 offer new paradigms for controlling elastic waves with subwavelength thickness, enabling fascinating phenomena, e.g. , extraordinary refraction, 8,9,14,15 source cloaking, 13 asymmetric transmission, 16,17 etc.…”

“…In particular, as a family of 2D versions of wave modulation metamaterials, elastic metasurfaces 8–17 offer new paradigms for controlling elastic waves with subwavelength thickness, enabling fascinating phenomena, e.g. , extraordinary refraction, 8,9,14,15 source cloaking, 13 asymmetric transmission, 16,17 etc. Most of the previous studies on elastic metasurfaces investigate the Hermitian domain, where the inherent material loss is neglected.…”

Reflective mode conversions between extensional and flexural waves by ultrathin oblique anisotropic tri-component resonators

“…In real application scenarios , elastic waves are constrained by solid surfaces, as an example, known as lamb waves in solid plates. Elastic metamaterials also could be used to manipulate the phases [16][17][18][19][20][21][22], amplitudes [23,24] or polarizations (wave modes) [26][27][28][29][30][31][32] for lamb waves. The Lamb wave contains two modes at low frequencies: the zero-order symmetrical mode (socalled "extensional mode") and antisymmetric mode (socalled "flexural mode") [33,34].…”

“…Chai et al [32] proposed a multi-modal interference theory and designed local res-(a) E-mail: paipeng@cug.edu.cn (corresponding author) onance metamaterial, which successfully achieved nearly full-mode transformation transmission between bending and longitudinal modes. So far, the structures in these pervious works [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] can work with comparable wavelength. As a result, these designs become unfeasible at low frequencies due to their large size.…”

“…Figures 3(b) and (c) give intuitive images for the size comparison. In previous related works [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], the size of the conversion device and the working wavelength are of the same order of magnitude. Our design is more feasible for low-frequency application scenarios.…”